Introduction: Immunization is the most effective means of improving health. In the absence of a proper and regular immunization program, people and especially children will be left at high risk of many infectious diseases. This study was designed to assess Expanded Program on Immunization (EPI) for mothers and children under 2 years old in Shahriar, South west of Tehran.

Materials and Methods: This research was a cross-sectional study. standard cluster sampling was applied to select 210 children in the age group 18-24 months old and 240 women with a child less than 1 year of age who were resident in Shahriar city. Standard formats were used for collection of the data. Descriptive and analytic tests (chi squares, Fisher exact-test, t test, ANOVA, bivariate and logistic regression module) were applied to analyze the data.

Results: The results showed that vaccination coverage in children was over 90 percent. 17.6 percent of the children were partially vaccinated and 41.4 percent were vaccinated completely but with more than one-month delay. The important character which was strongly associated with more than one month delay in immunization was center of childhood immunization. Although 83.8% of women with a child under 1 year age had received twice tetanus immunizations, only 13.3% of women had obtained the complete series of five immunization. The character which was associated significantly with dT immunization status was the length of time that mother had been living in Shahriar.

Conclusion: There are some barriers in vaccination delivery, including unefficient recall and follow up systems and scattered records of dT vaccination. These factors were statistically associated with immunization status and therefore some proper solutions against these barriers should be introduced. It is now time for a boost to be given to both quality and sustainability of appropriate immunization programs.